when you and i have to rush to work, only five hours a night, what happens is the body burns 5% more energy. you might say, wait a minute, that should help you lose weight, right? you're burning more. we all think that, we're awake. like an engine, we have to burn more, but, the hormones in the brain recognize that and they take in more. that is the problem. when you're in that active state, your body signals you to eat more. more of the wrong stuff. more carbohydrates, more fats. that's what they found in the study. when they let people sleep nine hours a night, they stopped eating so much carbohydrates and fats. we have hormones in the brain, jon, when to signal to shut off hunger but they become insensitive in setting like this where we're staying up too much. jon: the people in the study who slept less actually burned more calories and turned around and took even more calories than they had burned? >> much more. somehow they lost track of the fact, their bodies did, engine did, last track of the fact they had eaten enough. this is what we have long non. this explains why. it tells us we